1. Field of the Invention
This invention relates generally to promotion of growth in economically important animals. More specifically it relates to a method for accelerating the growth rate and simultaneously increasing the feed-utilization efficiency in such animals.
2. Description of the Prior Art
It is well-known that the acceleration of growth rates and an increase in the efficiency of feed utilization in economically important animals is an important consideration in agricultural economics. A faster growth rate allows greater use of the facilities employed in raising the animal, thus improving return on investment. An increase in the efficiency of feed utilization results in a lowered cost of production.
In the search for effective growth promotants, it is generally recognized that a relatively small improvement in growth rates and feed efficiency can be advantageous. Thus, for example, in broiler chickens a growth rate acceleration of 3% or more and an increase in feed efficiency of about 2% or more is economically worthwhile, particularly where the active compound is used in relatively small quantities and is favorably priced to the user.
Heretofore a number of compounds have been used as growth promotants for animals. Among such compounds are some antibiotics such as penicillin G, bacitracin, chlortetracycline, tylosin, lincomycin and flavomycin. It is known, however, that antibiotics vary in their effectiveness in stimulating growth and increasing feed efficiency and that some are effective for one purpose and ineffective for the other. Providing a compound which gives significant improvement in both rate of growth and feed-conversion efficiency would, therefore, constitute a significant advance in the art.
The antibiotic amphomycin is disclosed and claimed in U.S. Pat. No. 3,126,317. The production and properties of amphomycin are also described in Antibiotics and Chemotherapy, 3, 1239-1242 (1953), Antibiotics Annual 1954-1955, Medical Encyclopedia, Inc., New York, N.Y. at pages 1011-1019 and Antibiotic Medicine and Clinical Therapy, Vol. III No. 2, 142-145 (1956). None of the published literature on amphomycin, however, discloses use of this compound as a feed growth additive.
Amphomycin is an acid polypeptide and readily forms salts with pharmaceutically acceptable bases, e.g. the sodium, ammonium, calcium and aluminum salts. As used herein and in the claims the term amphomycin refers to the free acid or a pharmaceutically acceptable salt thereof.